litmus-rt.git - The LITMUS^RT kernel.

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The LITMUS^RT kernel.

Bjoern Brandenburg

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cdev); pwm_channel_writel(&led->pwmc, PWM_CUPD, led->mult * (unsigned) b); } /* * NOTE: we reuse the platform_data structure of GPIO leds, * but repurpose its "gpio" number as a PWM channel number. */ static int pwmled_probe(struct platform_device *pdev) { const struct gpio_led_platform_data *pdata; struct pwmled *leds; int i; int status; pdata = pdev->dev.platform_data; if (!pdata || pdata->num_leds < 1) return -ENODEV; leds = devm_kzalloc(&pdev->dev, pdata->num_leds * sizeof(*leds), GFP_KERNEL); if (!leds) return -ENOMEM; for (i = 0; i < pdata->num_leds; i++) { struct pwmled *led = leds + i; const struct gpio_led *dat = pdata->leds + i; u32 tmp; led->cdev.name = dat->name; led->cdev.brightness = LED_OFF; led->cdev.brightness_set = pwmled_brightness; led->cdev.default_trigger = dat->default_trigger; led->active_low = dat->active_low; status = pwm_channel_alloc(dat->gpio, &led->pwmc); if (status < 0) goto err; /* * Prescale clock by 2^x, so PWM counts in low MHz. * Start each cycle with the LED active, so increasing * the duty cycle gives us more time on (== brighter). */ tmp = 5; if (!led->active_low) tmp |= PWM_CPR_CPOL; pwm_channel_writel(&led->pwmc, PWM_CMR, tmp); /* * Pick a period so PWM cycles at 100+ Hz; and a multiplier * for scaling duty cycle: brightness * mult. */ tmp = (led->pwmc.mck / (1 << 5)) / 100; tmp /= 255; led->mult = tmp; pwm_channel_writel(&led->pwmc, PWM_CDTY, led->cdev.brightness * 255); pwm_channel_writel(&led->pwmc, PWM_CPRD, LED_FULL * tmp); pwm_channel_enable(&led->pwmc); /* Hand it over to the LED framework */ status = led_classdev_register(&pdev->dev, &led->cdev); if (status < 0) { pwm_channel_free(&led->pwmc); goto err; } } platform_set_drvdata(pdev, leds); return 0; err: if (i > 0) { for (i = i - 1; i >= 0; i--) { led_classdev_unregister(&leds[i].cdev); pwm_channel_free(&leds[i].pwmc); } } return status; } static int __exit pwmled_remove(struct platform_device *pdev) { const struct gpio_led_platform_data *pdata; struct pwmled *leds; unsigned i; pdata = pdev->dev.platform_data; leds = platform_get_drvdata(pdev); for (i = 0; i < pdata->num_leds; i++) { struct pwmled *led = leds + i; led_classdev_unregister(&led->cdev); pwm_channel_free(&led->pwmc); } platform_set_drvdata(pdev, NULL); return 0; } static struct platform_driver pwmled_driver = { .driver = { .name = "leds-atmel-pwm", .owner = THIS_MODULE, }, /* REVISIT add suspend() and resume() methods */ .probe = pwmled_probe, .remove = __exit_p(pwmled_remove), }; module_platform_driver(pwmled_driver); MODULE_DESCRIPTION("Driver for LEDs with PWM-controlled brightness"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:leds-atmel-pwm");


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